CD161. also known as KLRB1 or NKR-P1A, is a C-type lectin receptor encoded by the *KLRB1* gene. It is primarily expressed on natural killer (NK) cells, mucosal-associated invariant T (MAIT) cells, and subsets of T cells, including Th17 and cytotoxic CD8+ T cells. CD161 interacts with lectin-like transcript 1 (LLT1), its ligand, to regulate immune responses by modulating activation or inhibitory signals depending on cellular context. In NK cells, CD161 may act as a co-inhibitory receptor, dampening cytotoxicity, while in T cells, it can promote pro-inflammatory cytokine secretion.
CD161 antibodies are critical tools for identifying and characterizing these immune cell populations via flow cytometry or immunohistochemistry. Research highlights CD161's role in autoimmune diseases (e.g., multiple sclerosis, rheumatoid arthritis), infections, and cancer. For instance, elevated CD161+ T cells are linked to tissue inflammation, while its loss on tumor-infiltrating lymphocytes correlates with immune exhaustion.
Therapeutic interest in CD161 is growing, with studies exploring blockade strategies to enhance anti-tumor immunity. However, its dual role in immune activation and suppression complicates clinical translation. CD161 antibodies thus serve both as research reagents and potential biomarkers for disease progression or therapeutic targeting. Ongoing studies aim to clarify its signaling mechanisms and tissue-specific functions to unlock clinical applications. (Word count: 248)